This "prediction" is highly unremarkable. It has been what lots of people have been saying for weeks now, if the result were to turn out to be close. One thing about Trump is he is not subtle. He has more or less been telling anyone listening attentively that that is what he would do.
I do not for a moment believe the courts are going to stop the count for him. They may be Republican but they are still judges and they will not want to preside over a descent to a banana republic in civil war. Trump is just deploying the millionaires reflex: when you lose, send in the lawyers, and hope he that has the biggest chequebook wins. He will just have to wait.
The worry would be if he loses when the votes are all in, what he might hint people could do on the street to protest against his fake "fraud". I really have no idea. He's so erratic that I have no feel for whether he is interested in leading a street protest, or whether he would bluster and then go quietly. I suspect the latter. Donald "Heel Spurs" Trump does not strike me as a likely leader of a real insurrection. He seems to me more likely to want to make money as a far right TV talking head - if he stays out of jail.